Thank you all who replied to my thread! Your help is greatly appreciated.
In the following, I'll try to answer to all the suggestions and questions which have come up.
First of all my system information:
Operating System: Windows 7 Professional 64-bit (6.1, Build 7601) Service Pack 1 (7601.win7sp1_gdr.140303-2144)
Processor: Intel(R) Core(TM)2 Duo CPU P8700 @ 2.53GHz (2 CPUs), ~2.5GHz
Memory: 3072MB RAM
Direct X version: DirectX 11
Device
Name: ATI Mobility Radeon HD 3400 Series
Approx. Memory: 1496 MB
Current Display Mode: 1440 x 900 (32 bit) (60Hz)
Drivers
Main Driver: aticfx64.dll,aticfx64.dll,aticfx32,aticfx32,atiumd64.dll,atidxx64.dll,atiumdag,atidxx32,atiumdva,atiumd6a.cap,atitmm64.dll
Version: 10.1
Date: 4/30/2013
Direct X Features enabled: DDraw Status: Enabled
D3D Status: Enabled
AGP Status: Enabled
@ LightningLockey, the last time when Dragon Commander was running on my laptop (a few weeks ago) I did not encounter any overheating problems. It is only an issue with D:OS. I think that I have installed the best ATI video driver available for my graphics card - at least it does not automatically update the drivers when I am running a support tool.
Unfortunately, I do not have a cooling station. My laptop however does not stand just on the desk or so - when playing I always put it on two books (one on each side) so that there are at least a few cm empty space between the desk and the underside of my laptop. I am not really convinced that a real cooling station would make such a big difference but I could certainly give it a try.
As for "screaming" of the cooling fan: my cooling fan has an in-built noise reduction so that I never ever hear anything. I have already been wondering whether my cooling fan was working at all but judging from the hot air coming it should still be working. I admit, however, that I was probably not handling the cooling fan with all the care I should: I have a Lenovo laptop and I can replace the cooling fan for as little as 10 」 in 15 minutes. Which I should probably do next if my overheating problem with D:OS does not get better.
@Raze, I will send a report with my problem to Larian's support.
@Ellary, yes I do have a control center for my graphics card and I think everything should already be on minimum for D:OS. Thank you for the cooling station suggestion! I will give it a try!
@ NeutroniumDragon, I have already enabled the frame rate cap but I have not been messing around with vsync. I'll give it a try, thanks! To be honest, I am not quite sure whether it is my CPU or my GPU to blame for overheating - both temperatures continuously rise to 90 C and over. Hence, I do not know which one is eventually responsible for the shutdown.
Thank you all again for your suggestions!